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UNITED STATES PATENT OFFICE.

.IULES A. GROSSIOBD, FILS, OF PARIS, FRANCE, ASSIGNOR TO EDWARD E.

' KIPLING, OF NEW YORK, N. Y.

IMITATION DIAMOND.

SPECIFICATION forming part of Letters Patent No. 250,725, dated December 13, 1881.

Applicationfiled October 26, 1881. (No specimens.) Patented in France November 20, 1880.

to or other transparent material in which the back of the stone is rendered reflective by a silver deposit or other bright coating. The ordinary method of applying this coating is to deposit the silver from a solution of ammonia nitrate of 15 silver by means of a reducing agentby preference, tartrate of soda or potash, (sel de Seignette,) or tartaric acidthe face of the stone being protected by a mixture of rubber and gutta-percha. Thesilvercoating,byreflecting 2 o the rays transmitted through the stone, greatly increases its brillianey. Silver-foil has-been used for the same purpose. To protect this coating an alcohol or essence varnish which has no oxidizing effect upon the silver is ap- The present invention contemplatesnoimprovementinthispartofthemounting, but is designed to secure the stone, in a simple and inexpensive way, from being injured in handling, setting, or washing.

To makean imitation stone capable ofstanding the friction and washing to which it would ordinarily be subjected the stone has heretofore been set in a frame or box (culot) struclrup from a sheet of gold, silver, or other metal, so

5 as to fit the silvered and varnished portion of the stone. Notonly is thisadiffieult and costly operation, but, owing to a want of close adherence between the metal frame, or culot, and the varnish, the air and moisture are liable to en- 6 ter and the silver ultimately to become oxidized and its capacity as a reflector destroyed. These difficulties are avoided by the present invention, in which the stamped metal frame, or culot, is replaced by acoherentlayer of metal 5 deposited with or without the aid ofa galvanic and the protecting-coating of varnish, a layer or film of powdered plumbago, metallic paint, or other suitable material conductive of electricity, is applied to the varnish, and the stone is placed iii a solution ofcopper, and isineluded in a galvanic circuit, so that copper is deposited from the solution upon the varnish. When the deposited layer is thick enough, the stone is removed and plated with gold. The gold deposited upon the copper prevents it from oxidizing, while the latter gives strength to the envelope. The copper deposit, instead of being gold-plated, could be plated with silver, nickel, or other metal. Instead of depositing copper upon the varnish, other metal could be so deposited without departing from the spirit of this invention.

Although, as already stated, the invention relates more particularly to imitation diamonds made from glass, it is obviously applicable to all kinds of stones, natural or artificial, where it is desired to have their brillianey increased by a reflecting layer at the back.

I claim--- 1. In the manufacture ofimitation diamonds, or in the preparation of artificial stones, natural stones, or other like objects wherein the brillianey of the object isincreased by means of a reflecting-coating at the back, the improvement consisting in depositing a coherent layer of metal over said reflecting-coating, so as to form a protection thereto, substantially as described.

2. An imitation diamond or other like object having a reflective coating applied at the back and a protecting layer of metal deposited over said coating, substantially as described.

3. The combination, with the reflective coating and its protective varnish, of the exterior protective layer of copper or other metal deposited thereon and plated, substantially as described.

In testimony whereoflhave signed this specification in the presence of two subscribing witnesses.

JULES ANATOLE GROSSIORI), FiLS.

Vitnesses:

R0121. M. Hoornn, DAVID T. S. FULLER. 

